Author Topic: From no parts to decent stockpile, best approach?  (Read 318822 times)

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Offline Neganur

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Re: From no parts to decent stockpile, best approach?
« Reply #150 on: March 23, 2017, 05:34:04 am »
Don't buy that "mixed grilled" stuff unless you want a hobby like collecting and sorting stamps...
your time is used better in actual project in my opinion. I think it's better to buy proper assortments.

It can ofc be fun to sort stuff but in reality it's very rare you get parts that are actually useful unless you see something in a pile that makes it a bargain.
 

Offline Mr. Scram

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Re: From no parts to decent stockpile, best approach?
« Reply #151 on: March 25, 2017, 03:06:48 am »
Not too long ago I started stockpiling too and have found that is it really nice to have the common passives at hand. For those I can regularly find all sorts of uses. I also bought a large amount of classic op-amps and other ICs that seemed common or interesting. Those get used a lot less, because I tend to reach for superior modern day chips that are ordered specifically for the project, rather than building something with an outdated LM358. They are cheap as chips, though, and storing them takes little room, so it does not hurt to have them. They can be useful fixing things, but they are not as useful as the common passives.
 

Offline TheUnnamedNewbie

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Re: From no parts to decent stockpile, best approach?
« Reply #152 on: March 25, 2017, 08:28:23 am »
I don't know how common this is, but at my university, you can order parts from some suppliers, including farnell and RS, through our assembly/logistics team inside ESAT (EE dep.). This is, to my knowledge, is actually cheaper than getting stuff yourself from those distributors because the university gets price deals. There is a slight fee for the department, but even with that, I've orderd 15 euro's worth of parts on farnell and ended up having to pay 12 euros, even though the farnell price is without taxes and such (and if I orderd for myself I also had to pay shipping and stuff!). I believe this service is available to anyone, not just staff and students.

I have some basic parts, mainly through hole, if I want to breadboard stuff. Cheap, crappy chinese kit boxes of capacitors because I don't really care about how long they last.

Sure, I can get next day delivery on stuff, but when I'm working on a project on saturday, I want to work on my project then. As, for now, my projects aren't that complex, they can usually go from "Idea" to "finished breadboard and ready to design a pcb" in one weekend, next-day delivery still isn't quite enough. On day's I'm in my uni, I can also rely on the parts store in my department, where I can go buy stuff. Usefull for stuff like high-power resistors. They also store hundreds of 4000 and 7400 logic IC's, zeners, ....

For the same reason, I don't really stock SMT stuff, since I don't build my own PCB's either (get them from the same department at my uni, no soldermask tho...). If I have to wait a few days for them to build my pcb, I can also wait for 24 hours to get those parts.
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Online boffin

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Re: From no parts to decent stockpile, best approach?
« Reply #153 on: March 26, 2017, 07:40:57 pm »
Based on top my list above of basic passives/basic transistors, what would everyone add as basic starting components.  555?  TL071?  4016?  PC817?

I'm wondering if there's enough demand for someone to say to one of the Shenzen suppliers "make this pack for me", and sell them for $30



 

Offline james_s

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Re: From no parts to decent stockpile, best approach?
« Reply #154 on: March 28, 2017, 06:16:34 pm »
The basic passives are the most useful by far, resistors and capacitors in a whole range of values and a few different types, and organize them. I've spent countless hours of my life searching for that one resistor I forgot to order, maybe I need a 470 ohm and I'll find I ordered a 470k, then I'll rummage through my boxes and find 4.7 ohm, 47 ohm, 4.7k, 47k, everything but the part I need. It may only cost 2 cents but that's little help when I don't have it.

Having a few ICs is handy, 555, a few generic op-amps like the TL082, 2N3904 and 2N3906 transistors, some LM317s, depends what you're working on but those are parts I often use. I may find that I need something more specialized in the final circuit but I can do a lot with the basic stuff.

I agree that buying random assortments can be of limited value, although it's fun to go through them and see what there is. It's a great way for a kid with few resources who wants to experiment with electronics and it can be a creative process trying to design something interesting around an assortment of parts one already has, but I wouldn't buy a ton of random bits just hoping they'll be useful some day.
 

Offline scorched

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Re: From no parts to decent stockpile, best approach?
« Reply #155 on: April 07, 2017, 04:23:52 pm »
I am by no means an expert, as I am just returning to the world of electronics from my days in the military 20 years ago.  But what I did to acquire my stockpile, was to find places that sold them as bundles.
And specifically I have bought several "boxes" of scrap parts, as well as some specific packages from gold mine. Sometimes they have deals that are worth taking many times not.

For $8USD I ordered this, and while a lot of it is junk, once I sorted it all, I ended up with a good amount of decent items.
http://www.goldmine-elec-products.com/prodinfo.asp?number=G9321
Here is an example, each pack is only $2.50USD
http://www.goldmine-elec-products.com/products.asp?dept=1053.
Also look in the assortments for specifics.
http://www.goldmine-elec-products.com/departments.asp?dept=1409
And for shear fun I purchased a surprise RCA parts box, mostly cap, coils, and resistors, but a few kinds each eeprom, transistors and such. Had over 150 items.
http://www.goldmine-elec-products.com/prodinfo.asp?number=G21550
If you get this pack, you get a little better selection but limited to 50 items but I did not acquire this one.
http://www.goldmine-elec-products.com/prodinfo.asp?number=G19894A

So all said, I spent about $30, and consider myself pretty much fully stocked for my return to electronics.

Already repaired my Denon AVR4806 with what I ordered, maybe I got lucky, but anyway I am happy.

Cheers!
 
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Offline dimkasta

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Re: From no parts to decent stockpile, best approach?
« Reply #156 on: April 08, 2017, 12:27:09 pm »
I did not read the entire thread, just the last page, so excuse me if it's already been mentioned.

Don't forget to get a bunch of the old trusty lm7805 and lm317s :)
 

Offline Mr. Scram

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Re: From no parts to decent stockpile, best approach?
« Reply #157 on: April 08, 2017, 07:59:39 pm »
Don't forget to get a bunch of the old trusty lm7805 and lm317s :)
Other than them being well known, are they really still viable? The drop-out is quite high by modern day standards and they tend to piss away power too. It is good to get to know them, but they aren't really recommended for any circuit that has to perform.
 

Offline james_s

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Re: From no parts to decent stockpile, best approach?
« Reply #158 on: April 08, 2017, 08:27:37 pm »
There's nothing wrong with a 78xx, I still see them occasionally in modern-ish devices. I wouldn't hoard hundreds of them but it's handy to have a few common types on hand. 7815 and 7915 are handy if you want to make analog audio devices, hard to beat an old fashioned linear power supply for clean DC.
 

Offline dimkasta

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Re: From no parts to decent stockpile, best approach?
« Reply #159 on: April 08, 2017, 11:24:48 pm »
Other than them being well known, are they really still viable? The drop-out is quite high by modern day standards and they tend to piss away power too. It is good to get to know them, but they aren't really recommended for any circuit that has to perform.

All valid arguments, but I thought we were talking about a stockpile for general experimentation.
There is nothing wrong with them unless the design is sensitive to high-frequency dirt and noise. But then we would not be talking about quick experimentation using stockpiled stuff. We are talking about a device that needs a purpose-designed PSU.
Of course, some LT stuff might probably be a good idea too, but they tend to be lower voltage, way more expensive and far less available.
 

Offline TheUnnamedNewbie

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Re: From no parts to decent stockpile, best approach?
« Reply #160 on: April 12, 2017, 01:30:44 pm »
Other components that I like to keep around, that might not be so common: Some power resistors! They can serve as quick loads for testing powersupplies or power switching circuits. I like to keep at least 10 .1 Ohm, 1 Ohm and 10Ohm 2W resistors around, and am looking at stockpiling some more.
The best part about magic is when it stops being magic and becomes science instead

"There was no road, but the people walked on it, and the road came to be, and the people followed it, for the road took the path of least resistance"
 

Offline karoru

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Re: From no parts to decent stockpile, best approach?
« Reply #161 on: May 02, 2017, 05:45:53 pm »
Other components that I like to keep around, that might not be so common: Some power resistors! They can serve as quick loads for testing powersupplies or power switching circuits. I like to keep at least 10 .1 Ohm, 1 Ohm and 10Ohm 2W resistors around, and am looking at stockpiling some more.

They're especially useful if you need to deal with AC from time to time and your schmick DC electronic load renders useless. I tended to use small halogen bulbs, but one learns quickly that they tend to get quite hot quite quickly and in the middle of experimentation it's surprisingly easy to forget that this tiny piece of glass has been glowing white and dissipating 10W few seconds ago. If someone deals with audio stuff then 4 or 8 ohm beefy non-inductive power resistors will serve dual role.
 

Offline dimkasta

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Re: From no parts to decent stockpile, best approach?
« Reply #162 on: May 02, 2017, 08:03:05 pm »
And of course MANY 3mm screws (plastic and metal), nuts, washers, standoffs, and spacers.
Mica insulators for TO220 or whatever package you like using
Fuses and fuse holders
Battery clips
crimp connectors and a press
 

Offline Creative

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Re: From no parts to decent stockpile, best approach?
« Reply #163 on: May 19, 2017, 12:52:17 am »
Here is how I spent momey on my electronics lab.  When i design a circuit and I plan to bread board it (as opposed to the dead bug method) I use 1/2 watt resistors even if the power allows for a safety margin with a 1/4 watt equivalent because they make a better electrical connection. If i decided to make a permanent version I will go back to the 1/4 watt power rated resistors. 
  I store the 1/4 and 1/2 watt resistors of the same value in same drawer of my collection. I also use pegboard hooks and 10 compartment plastic boxes to store parts.  These boxes have a plastic hook for vertical mounting and label the side of the box with a general description of what is in the box.  I store switches, capacitors, bipolar transistors and other electromechanical parts in them I also have ESD safe plastic storage boxes storing jfets, micro controllers, and other static sensitive parts. I use a earth grounded wrist strap when working with esd parts on my grounded work mat.  These small parts boxes are nice because they do not take up much room on the bench and they easily hang out of the way
 

Offline KL27x

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Re: From no parts to decent stockpile, best approach?
« Reply #164 on: June 08, 2017, 04:51:12 am »
Quote
I'm gradually migrating to use of a lot of Ziploc-style bags, of many different sizes, some quite small.  These waste virtually no space, if you press the air out before sealing.

The end game, imo, is a heatsealer. Polyethyne is great. U can size down the bags that digikey sends u, just big nuff to hold the entire part number and such. Metallic bags are extra special... u can partition them into multiple sections, and they dont fall apart. I will cut the end with a small incision to take out the cut tape or loose parts, and seal the end back up with soldering iron when done.
 
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Offline Cliff Matthews

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Re: From no parts to decent stockpile, best approach?
« Reply #165 on: June 08, 2017, 11:26:53 am »
A heatsealer, i have the nichrome wire.. Any chance you could post a photo of how you made yours?
Also, how do you stop the plastic from sticking to the wire?
 

Offline neslekkim

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Re: From no parts to decent stockpile, best approach?
« Reply #166 on: June 08, 2017, 02:35:59 pm »
A heatsealer, i have the nichrome wire.. Any chance you could post a photo of how you made yours?
Also, how do you stop the plastic from sticking to the wire?

Normal heatsealers for bags use some sort of teflon tape over the heatingwire
Loads of cheap "impulse sealers" on ebay
 

Offline CharlieWorton

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Re: From no parts to decent stockpile, best approach?
« Reply #167 on: June 09, 2017, 04:18:28 am »
For new parts, AliExpress or BangGood are both good sources.  I have more success (lower prices, better selection) with AliExpress.  Both companies are equally reputable, I've never had a problem with either.  For used stuff, run a free ad in a local advertiser offering free pickup and disposal of unwanted electronics - old computers, printers, whatever.  There are decent stepper motors in some printers, the power supplies in old computers still work well (usually).  If you have more time than money, this can be a decent way to acquire some unusual stuff.  In addition, you might be able to repair and sell some broken electronics, if you're so inclined.
 

Offline brainwash

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Re: From no parts to decent stockpile, best approach?
« Reply #168 on: June 10, 2017, 10:34:02 pm »
Not sure if this is new, it was probably discussed above, but stockpiling needs an organised approach:
- stockpile base components (capacitors, resistors, LM324, 74*, 555, resonators, fuses, SMD 0805, ....)
- do not stockpile 'best and greatest' components. That includes any ARM chip, any PIC chip, ADCs, FPGAs, ...
- stockpile connectors - they are likely to be needed at any time: USB, mini-USB, micro-USB male, USB cables, Sub-9, ...
- stockpile wires - any size, any number of conductors under the insulation, any color (preferably all, including dual-color)
- stockpile base logic: breadboards, Arduino Uno [clones], Digistamp [clones], BT, ESP8266

The above would let you fix a lot of issues if you have broken device. It will also let you prototype almost any idea.
Avoid buying into the latest and greatest, unless you are a technical head at some company. Most of the time, the things you will know how to use will be the ones that are the cheapest and people tend to use the most (ATMega328, ESP8266).
I have a pile of TI and Microchip stuff that I've rarely used. At least TI can be used with Energia, but most of the times you want to fail fast and fail often. This means you don't want to be wasting 1-2 days to get a chip working only to prove that your idea is wrong.

Aside from that, a good digital scope (or a mediocre analog one and a mediocre digital one) will get you far. You'll use the multimeter a lot more than those. You'll use your soldering station more. You'll use clips and clamps and wires even more. You'll use a digital analyzer, a hot-air station and signal generator a few times per year, at most. That is, considering your question. So plan your stockpile according to that.
 
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Offline schmitt trigger

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Re: From no parts to decent stockpile, best approach?
« Reply #169 on: June 24, 2017, 12:35:59 am »
This thread is loooong, and I essentially skimmed thru it.

But I think relays have not been mentioned. If you would like to control lights, motors, etc., in a safe and straightforward manner, relays are the way to go.
Get 5v-coil relays for the smaller sizes, and 12v-coil relays for the larger sizes.

From time to time you will find that your regulator, transistor, Triac, etc are overheating. Get some small TO220 heatsinks. It is surprising how much more power you can dissipate from a device with even a small heatsink, as compared to stand alone.
 

Offline brainwash

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Re: From no parts to decent stockpile, best approach?
« Reply #170 on: June 24, 2017, 12:47:34 am »
Cheap relays can be found from the scrapyard, you can get at least 10 for 1$. Some of them are timing relays (for example diesel heater) so not so easy to use. Anyway, most of the manufacturers these days have went the MOSFET way, and for a good reason: the old relays are both unreliable and fail in an uncontrolled way.
Still the cheapest and simplest way to get DPDT, if you need it. But in my experience relays tend to fail both randomly and in strange ways (i.e. one contact working 90% of the time).
 

Offline Jellysfish

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Re: From no parts to decent stockpile, best approach?
« Reply #171 on: August 17, 2017, 05:34:57 pm »
My local melvac sometimes sells general electronics in a grab bag--slightly more expensive than online but at least these parts are more likely to be new
 

Offline TheDane

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Re: From no parts to decent stockpile, best approach?
« Reply #172 on: August 26, 2017, 07:22:27 am »
Recycling old equipment is also a nice way to get components.

Instead of 'throwing' out old/broken stuff, I usually keep it around for scraps - and when I need something I don't have already in my assortments - I will take a look at the old junk, and surprisingly I often find what I am looking for.  :-+
 
If I can solder it in, I can solder it out  :-/O
 

Offline kobaz

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Re: From no parts to decent stockpile, best approach?
« Reply #173 on: September 25, 2017, 05:07:42 pm »
Adding a question to the pool.

For capacitors and the like I get the importance of quality.  It's good to avoid the exploding type, etc.

Things like transistors.  How important is it to get high quality transistors from known brands?

For example if I wanted a PNP 2N3906:
https://www.digikey.com/products/en/discrete-semiconductor-products/transistors-bipolar-bjt-single/276?k=2N3906&k=&pkeyword=2N3906&v=497&pv69=80&mnonly=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=500

These are 44 cents each USD.  Versus:
https://www.amazon.com/dp/B06Y49GB3F

I can get 675 transistors at 2 cents each on amazon.  Are they going to catch my bench on fire?  Are they going to produce excessive noise?  Anyone familiar with these?

 

Offline JoeN

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Re: From no parts to decent stockpile, best approach?
« Reply #174 on: September 25, 2017, 10:24:18 pm »
For example if I wanted a PNP 2N3906:
https://www.digikey.com/products/en/discrete-semiconductor-products/transistors-bipolar-bjt-single/276?k=2N3906&k=&pkeyword=2N3906&v=497&pv69=80&mnonly=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=500
These are 44 cents each USD.

3904/3906's can be 2 cents each if you buy in bulk/know where to look. 

http://www.newark.com/micro-commercial-components/2n3906-ap/bjt-pnp-40vdc-to-92/dp/69R6840

The SMT versions can be one cent each. 

http://www.newark.com/on-semiconductor/mmbt3906lt3g/bipolar-transistor-pnp-40v-sot/dp/98H0752

I would think the people building kits are getting components from sources that are buying in huge quantities.  The Chinese seem to do it that way (small guys knowing a big guy and getting in on orders so they can get big guy prices for kits to sell on eBay, etc.).  All the other transistors offered, I don't know, not much is as cheap as a 3904/3906.
« Last Edit: September 25, 2017, 10:32:52 pm by JoeN »
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